Field of the Invention
The present invention relates to a substrate and an electronic device. The present application claims priority to Japanese Patent Application No. 2016-046988 filed on Mar. 10, 2016 and Japanese Patent Application No. 2016-234450 filed on Dec. 1, 2016, and the entire contents of which are hereby incorporated by reference.
Description of the Background Art
Graphene is a material in which carbon atoms form an sp2 hybrid orbital and the carbon atoms are bonded two-dimensionally. Graphene in which carbon atoms are bonded in such a condition has a feature that the carrier mobility is remarkably high. Therefore, by use of a graphene film as a channel of an electronic device such as transistor, for example, the electronic device is expected to be increased in switching speed.
An electronic device in which a graphene film is used as an electrically conductive portion (channel for example) can be manufactured by forming a substrate including the graphene film and forming electrodes or the like on the substrate. The substrate including the graphene film can be formed for example by bonding to a support substrate a graphene thin film exfoliated from graphite, or bonding to a support substrate a graphene thin film grown by CVD (Chemical Vapor Deposition).
In order to ensure an acceptable production efficiency in mass production of electronic devices, it is preferable to use, in the above-described substrate, a support substrate having a large diameter (having a diameter of two inches or more, for example). In the substrate formed through a procedure including bonding of a graphene film as described above, a large region without the graphene film is included in the surface of the support substrate. In such a case, a process for manufacturing an electronic device, such as positional alignment for forming electrodes, is difficult to automate. A resultant problem is that mass production of electronic devices in which the aforementioned substrate is used is difficult.
In contrast, a method has been proposed according to which a substrate made of SiC (silicon carbide) is heated to desorb Si atoms and thereby transform a surface layer of the substrate into graphene, and accordingly the substrate in which the graphene film is formed on a support substrate is produced (see Japanese Patent Laying-Open No. 2015-48258 for example). Thus, in the main surface of the substrate, the region without the graphene film is reduced. As a result of this, mass production of electronic devices in which the substrate is used is facilitated.